The use of mobile telephones, notebook personal computers, electronic dictionaries, and other electronic information devices has recently become widespread. In terms of software, various types of software have been developed and installed in these electronic information devices to increase performance, and in terms of hardware, progress has been made in reduced size, reduced weight, and design implementation. Hardware size reduction, weight reduction, and design implementation have been developed the most in mobile telephones in particular, and various types of mobile telephones have been proposed (see Patent References 1 and 2 below, for example).
FIG. 14 shows the folding mobile telephone described in Patent Reference 1, wherein FIG. 14A is a perspective view, and FIG. 14B is a partially enlarged perspective view showing the hinge mechanism.
The folding mobile telephone 80 is composed of a cover body case 82 provided with a display part 81, a speaker, or the like; a main body case 84 provided with a wireless transceiver circuit and various types of operating keys 83, a microphone, or the like; and hinge mechanisms 85, 85′; and has a structure in which the cover body case 82 and the main body case 84 are connected to each other by the hinge mechanisms 85, 85′ so as to be able to fold together.
The hinge mechanisms 85, 85′ are composed of the hinge mechanism 85 shown in the right side of FIG. 14A, and the hinge mechanism 85′ shown on the left side of FIG. 14A. Among these hinge mechanisms, a first bridge part 84a that protrudes from the right-side hinge mechanism 85, and a first bridge part 82a that protrudes from the cover body case 82 are disposed on the same axis in the main body case 84, and a hinge assembly 86 is fitted into the center holes of the first bridge parts 84a, 82a. In the left-side hinge mechanism 85′, a second bridge part 84b that protrudes from the main body case 84, and a second bridge part 82b that protrudes from the cover case 82 are disposed on the same axis, and a hinge shaft 87 is fitted into the center holes of the bridge parts 84b, 82b. As shown in FIG. 14B, the hinge assembly 86 fitted into the center holes of the first bridge parts 84a, 82a is composed of a main body drive unit 88 that rotates integrally with the main body case, and is connected to an end part of the main body case 84; a cover body drive unit 89 that rotates integrally with the cover body case, and is connected to an end part of the cover body case 82; a motive mechanism (not shown) disposed between the main body drive unit 88 and the cover body drive unit 89, for exerting a force for rotating the cover body drive unit 89 in the opening direction of the cover body case 82; and a maintaining mechanism for maintaining the cover body case 82 in the closed position when the cover body case 82 is in the closed state.
Through the use of such a hinge mechanism, the cover body case 82 can be smoothly opened and closed in folding fashion with respect to the main body case 84 in the folding mobile telephone of Patent Reference 1.
FIGS. 15 and 16 show the folding mobile telephone described in Patent Reference 2, wherein FIG. 15 is an exploded perspective view showing the mobile telephone, FIG. 16A is a side view showing a state in which the mobile telephone case is folded together, FIG. 16B is an enlarged sectional view showing the portion to which the hinge mechanism of the mobile telephone is provided, and FIG. 16C is a partial enlarged sectional view along line X-X in FIG. 16B.
The folding mobile telephone 90 is provided with a transmitter case 91 composed of a pair of housings 91A, 91B; a connecting member 92 connected so as to be capable of rotating about a first rotational axis L1 to a housing part 91C that is formed at one end part of the transmitter case 91; a receiver case 94 composed of a pair of housings 94A, 94B and connected to a housing part 94C formed at one end thereof, so as to be capable of rotating about a second rotational axis L2 that is parallel to the first rotational axis L1 of the connecting member 92; wherein the transmitter case 91 and the receiver case 94 are connected to each other by the connecting member 92, and can rotate at the same angle as each other in opposite directions.
The transmitter and receiver cases 91, 94 are in thin rectangular shapes, accommodating concave parts are formed at both end parts in the longitudinal direction of the housing parts 91C, 94C, pairs of housing concave parts are provided on the extension lines of the first rotational axis L1 and the second rotational axis L2 at both end parts in the longitudinal direction of the connecting member 92, and a pair of first hinges 95A, 95A and a pair of second hinges 95B, 95B are accommodated in the accommodating concave parts. The first hinges 95A, 95A are disposed in the housing concave parts of the connecting member 92 and the transmitter case 91, and the second hinges 95B, 95B are disposed in the housing concave parts of the connecting member 92 and the receiver case 94, whereby the connecting member 92 and the transmitter case 91 are connected so as to be capable of rotating, and the connecting member 92 and the receiver case 94 are connected so as to be capable of rotating.
The connecting member 92 rotates from the folded position to the final opened position with respect to the transmitter case 91. At this time, in the folded position, the connecting member is restricted by coming in contact with a first contacting surface 97 composed of a wall surface that extends in the minor axis direction of the transmitter case 91 among the wall surfaces that partition the housing part 91C. In the opened position, the connecting member 92 is restricted by coming in contact with a second contacting surface 98 formed on the end positioned on the external edge part in the minor axis direction of the housing part 91C.
According to this configuration, since a fixed rotational sequence is always maintained for the rotation of the connecting member with respect to one case of the transmitter and receiver cases, and for the rotation of the other case with respect to the connecting member, folding and opening can be performed smoothly without imparting discomfort to the user.    Patent Reference 1: Japanese Laid-open Patent Application No. 2001-251396 (FIGS. 2 and 5, paragraphs 0016 through 0021)    Patent Reference 2: Japanese Laid-open Patent Application No. 2004-308710 (FIGS. 2 through 5, paragraphs 0010 through 0015)